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<div class="titlepage"><div><div><h3 class="title">
<a name="range.concepts.bidirectional_range"></a><a class="link" href="bidirectional_range.html" title="Bidirectional Range">Bidirectional Range</a>
</h3></div></div></div>
<a name="range.concepts.bidirectional_range.notation"></a><h5>
<a name="id650256"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.notation">Notation</a>
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<p>
<code class="computeroutput"><span class="identifier">X</span></code>
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<p>
A type that is a model of <a class="link" href="bidirectional_range.html" title="Bidirectional Range">Bidirectional
Range</a>.
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<code class="computeroutput"><span class="identifier">a</span></code>
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Object of type X.
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<a name="range.concepts.bidirectional_range.description"></a><h5>
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<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.description">Description</a>
</h5>
<p>
This concept provides access to iterators that traverse in both directions
(forward and reverse). The <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code> iterator must meet all of the requirements
of <a href="../../../../../../libs/iterator/doc/new-iter-concepts.html#bidirectional-traversal-iterators-lib-bidirectional-traversal-iterators" target="_top">Bidirectional
Traversal Iterator</a>.
</p>
<a name="range.concepts.bidirectional_range.refinement_of"></a><h5>
<a name="id650403"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.refinement_of">Refinement
of</a>
</h5>
<p>
<a class="link" href="forward_range.html" title="Forward Range">Forward Range</a>
</p>
<a name="range.concepts.bidirectional_range.associated_types"></a><h5>
<a name="id650426"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.associated_types">Associated
types</a>
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Reverse Iterator type
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<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
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<p>
The type of iterator used to iterate through a Range's elements
in reverse order. The iterator's value type is expected to be the
Range's value type. A conversion from the reverse iterator type
to the const reverse iterator type must exist.
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Const reverse iterator type
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<p>
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span> <span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code>
</p>
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<p>
A type of reverse iterator that may be used to examine, but not
to modify, a Range's elements.
</p>
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<a name="range.concepts.bidirectional_range.valid_expressions"></a><h5>
<a name="id650581"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.valid_expressions">Valid
expressions</a>
</h5>
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Name
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Expression
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Return type
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Semantics
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Beginning of range
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<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code>
</p>
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<p>
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code> if <code class="computeroutput"><span class="identifier">a</span></code>
is mutable <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
<span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code> otherwise.
</p>
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<p>
Equivalent to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">a</span><span class="special">))</span></code>.
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End of range
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<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rend</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code>
</p>
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<p>
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code> if <code class="computeroutput"><span class="identifier">a</span></code>
is mutable, <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="keyword">const</span>
<span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span></code> otherwise.
</p>
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<p>
Equivalent to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_reverse_iterator</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">a</span><span class="special">))</span></code>.
</p>
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<a name="range.concepts.bidirectional_range.complexity_guarantees"></a><h5>
<a name="id651042"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.complexity_guarantees">Complexity
guarantees</a>
</h5>
<p>
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code> has
the same complexity as <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code> and
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rend</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code> has the same complexity as <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code> from
<a class="link" href="forward_range.html" title="Forward Range">Forward Range</a>.
</p>
<a name="range.concepts.bidirectional_range.invariants"></a><h5>
<a name="id651182"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.invariants">Invariants</a>
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Valid reverse range
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For any Bidirectional Range a, <code class="computeroutput"><span class="special">[</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">a</span><span class="special">),</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rend</span><span class="special">(</span><span class="identifier">a</span><span class="special">))</span></code>
is a valid range, that is, <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rend</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code> is reachable from <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span></code>
in a finite number of increments.
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Completeness
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An algorithm that iterates through the range <code class="computeroutput"><span class="special">[</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rbegin</span><span class="special">(</span><span class="identifier">a</span><span class="special">),</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">rend</span><span class="special">(</span><span class="identifier">a</span><span class="special">))</span></code>
will pass through every element of <code class="computeroutput"><span class="identifier">a</span></code>.
</p>
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<a name="range.concepts.bidirectional_range.see_also"></a><h5>
<a name="id651431"></a>
<a class="link" href="bidirectional_range.html#range.concepts.bidirectional_range.see_also">See also</a>
</h5>
<p>
<a class="link" href="../reference/concept_implementation/semantics/metafunctions.html" title="Metafunctions">Implementation
of metafunctions</a>
</p>
<p>
<a class="link" href="../reference/concept_implementation/semantics/functions.html" title="Functions">Implementation
of functions</a>
</p>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003 -2010 Thorsten Ottosen, Neil Groves<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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